Making portland cement



pos'its'containingnp to 3% P 05 whose geomaterial in 'a-sufficient amount. But in the Patented Nov. 11, 1930 r I l r,

v uniranfsmmg PATEN i oFncEai f V nnnnnnicx w. HUB R,- or nivnnsinn, CAIlIIiOitNiA v MAKING ron rtnnn eniuenr n Drawing. Atyplication'filed March 19, 193501 semiin;' .337327%.

Portland cement is ordinarily prepared by when made into concrete and maintained at a calcining'and clinkeringa finely ground mixtemperature below 60"Fz, would refuse to turecontaining calcareousmaterial and clay set up. 1 I orother argillaceous material in certain pro- Now I have found that the presence ofeven 5 portions and grinding the product to such a 1.5% of P in theraw cement mix raises fineness as to impart hydraulic properties the clinkering temperatureabove that usually thereto. V employed in burning cement. In fact raises So far as I am'a'dvised calcareous material it to a point which cannot economically be containing any substantial pro-portion of attained in a rotary kiln, i. e. to 1500- C.

P 0 (or phosphates) has not been success- But eventhis'increase in temperature does fully usedin the'manufacture of Portland notserve to give complete combination, uncement. i less the clinker is ground and reburned'a ee:

It has long been known by those familiar 0nd time atthis temperature, which would with the art thatcements made frommarl or only give a fair grade o fcement.

limestone containing P 0 are slow setting i Ihave found thata mineralizer is 'neces-' and very slowhardening if'the cement consary,'i. eta substance which stimulates and tains more than 1% P 0 Furthermore brings about the'combinati'on of the various these cements are 'so diificult tojburnthatthe substances to form definite mineral entilime content must be carried s'o'low o get an ties, such as the all important mineral, trieconomical burning temperature that the calciumsilicate,3CaO SiOg uponwhichde- 70 r product is inferior to the cement carrying a pends the virtue andhardeni'ng properties of higher'lime content and containinglittle or Portland cement. i l I" no P 0 so much so that their utility is much Ordinarily such mineralizers' as I Fe O 1 restricted. There are marl and limestone deand A1 0 are found associated with the-raw 5 graphical locations would give them a subv presence of P Q these mineralizers are constantial advantage in cost of manufacture verted into iron phosphate (and possibly and distribution if the disadvantageof-the aluminum phosphate) which-has avery high P 0 content couldbe overcome. melting point which. makesfthis jfiuxingac- 1 The object of my'invention is a process tion practicallynil. So'thatthe fluxing or 0 which would make available such'deposits for mineralizing action of the 'Fegog has been the manufacture of Very superior Portland defeated by theP O present in the raw cement. i i T mix, and as aconzsequencea much higher I have studied in particular amarl 0on temperature would 'be necessary, to bring i taining 2% P 0 in theform of tricalcium aboutthe chemical combination into cement 3 phosphate. A raw cement mix proportioned minerals. V v

to give a high lime cement was compound- By the present invention it is readily posed from this material and clay, and this mix sible to produce a high grade Portland cewasburne'd to givea good appearing clinker ment which will harden readily, by using 49 in the usual manner'in a rotarykiln on an any suitable argillaceou'smaterialsuch as 90 operating scale. Thefresulting clinker conclay, in the amount needed, and using a caltained 4.5% of free lime," ('unco nbined CaO) 'careous material which may contain up to and the cement produced by grinding this 2 or 3%, or even slightly'more,;of P 0 and would notpass the'boiling test and the early by using an amount of ferric oxide or other strength ofthemortar made therefroniwas substance furnishing iron, inainount some- .9

' 59 what is customary; Furthermore the cement rotary. kiln, say 1300 14:00" Q; r i

"below the requirements of standard specifiwhat more than the chemical equivalent of cations'notwithstanding the Lfa'ct that the the'phosphoricacid radical present, bythe v ,clinker'was ground toa; fineness much'in exordinary burning method in a rotary kiln, cess of the usual requirements and far above and at temperatures readily attainable na In the case of a particular factory which waserected for the. manufacturejof'Portland cement, it was found that the cement refusedto set up properly due to the fact that the limestone which they were using contained a substantial 7 amount of phosphoric acid and as a result it wasfound'necessary.

to ship in phosphate-free raw materials from a considerable distance, although iron ore was available at a mine only a few miles away. 7 Q 7 As a specific example of the presentin;

Vention, a 1 cement raw mix: was made from phosphatic marl and :clay analysis given i fiaictoryg; A- portion of the-clinker "when ground to mesh andjreburned at1500 CI,

gave a clinker: containingv about 0.5% of free lime and the-icement whilegreatly improved,

was only of fair quality.

1 .To. another portion of the same raw mix Y 1.2% offerricoxide was added and the mixturewa's then calcinedand fclinkered by a a, v 4 a a heating it in a rotary kiln, tg abontingf'withargillaceous material at usual cement burning temperature and pulverizgiving upon-grinding, a cement of; excellent The analysis ofvthe originalirawinix (be- I 5 fore adding; the iron oxide) I the first; clinker? and the;-iron clinker? (clinker produced are as" follows Iron clinker" v 97 i clinker" will be se en'thatiin the present inventiofn" it is possible to overcome the defects of the cement prodlfl'c'ed-f when] burning "crude raw material containing the phosphoric acid radical,.'by converting the entireamo'untfof phosphoric? acid? into ferric phosphatejwhich 1 is substantially inert under these conditions,

,Pzoa ijn; the raw min i and leaving enough additional-5 iron oxide to, actas amineralizerluf The amount of iron 'oiiiicl ferric oxide),jso combining 'will; be

about 1.1

l lhaveiabovereferred i Q "h wea s the;raw-,mii, OfFQ O ingt h mform ,of iroii V oref, Othr iron -containing ma eri aliwhic'h w l ferric ox d T6 1, be; mp y s .19

as,'ferrous-marbonate; oreg lsoasted pyrites, v clavs or QSI-idh in. ro 3wa teimetallurthereafter the 'm xtuteeundessthk' 'gical materials orresidues from ore concentration or rolling mill scale wh ch contains substantlal amounts of iron, and the like,

or in fact various products or materials,

which during the clinkering operation would be'converted into ferricoxide, can be used for this purpose.- 1

. What} has-beensaidk above about the disadvantage of P 0 in marl is equally appli cablein the. case oflimestone, chalk, and

blast furnaceslag, smother calcareous mathat making a satisfactoryv Portlandicement} from any raw materials containing ,phosw V phate is readilypossible by addingtheirpn containing mater al; insuohamount as -toi convert all of the P 0 into ferricphose phate and to. have .asuflicient excess toi act asamineralizeny .7

LI claim ze 1. In the manufacture-of I ortland. cement from a raw materialwhich contains calcium, phosphate. 1n substantlal amounts .andy 1n WlllCll the minerallz ng components are '11 toosmallw mementby;

ing, th e=herein described improvement which 7 comprises 1 adding argfllaceousr material to the said material, antl]addinggan iron oxide. ma,- terial-v in suchamount as to; bring the. total by the addition of ferric oxide burning) iron content jup to substantially above the V cement burning temperature and under conditions capable: of converting substantially V the entire amount 1 of phosphate radical into iron phosphate]; While; leaving a substantial amount of iron oxide to actasv a mineraliaing' agent for the cement, and thereafter reducing the burnedimaterial to a fine powder,

' '2. In the manufactureofPortland cement V from phosphatio marl and clay, the herein de; 1

scribed step of adding iron o'xide- -materia l to I theimarl, in amount more than the ex'cess of' P phoric marl. H v a a 7 .3, I 11a ,ing cement. f a .vphoflsphmip i is acidradical oveniron oz'gidein the raw mix,the step "of vclinkering such raw miX,'-w hi1e associated i-with'enough iron"com-- p u to e t, all B2 tints "iron P1108 P conta Ph p i n tab eproper hyth 7 ate, and enough excess -.of :iron compounds g toconstitute a mineralizer.

s ep f co po t n a m e s ate ia th itl-i, ..inj-,-su ch; amount as to bring I the usual cement-burning conditions, whereby the phosphate content of the mix is converted into ferric phosphate, and the residual iron becomes effective as a mineralizer.

5. A Portland cement having at least moderately quick hardening properties, containing phosphoric acid Wholly in the form of iron phosphate.

In testimony whereof I aflix my signature.

FREDERICK W. HUBER. 

